The invention concerns a control device for a medical test system which has a lancing element that can be inserted into body tissue to collect body fluid, a lancing drive for the lancing element, a sensor element for body fluid arranged on the lancing element, and a control unit coupled to the sensor element. In particular, the invention concerns detecting a fault when collecting body fluid.
The repetition of a lancing process to improve blood collection is known for lancing aids with disposable lancets. If the first puncture does not result in an adequate drop of blood, the user tensions the lancing aid again and makes a second puncture with the same lancet which, if necessary, is deeper. The disadvantage of these mechanical lancing devices is the control by the user who must ultimately decide whether to repeat a puncture. The time that has elapsed between two punctures is correspondingly large, typically 10 to 20 seconds, and can hardly be shortened.
A more rapid repetition of punctures is conceivable using electrically operated lancing aids in which the tensioning and/or the actual puncture are initiated by electromechanical components. In EP-A 1 982 653 it is proposed that a check of the success of blood collection is interposed after the first puncture with a lancing element. This should enable the user to manually collect a sample. This type of feedback is achieved by a test element integrated into the blood collection system which is designed to generate a measured value with the blood collected from the first puncture. Such blood sugar measuring systems are therefore also referred to as integrated spot monitoring (ISM) systems. However, such ISM systems must be able to take into account the different skin types as well as human operator errors during blood collection without overburdening or impairing the user. Frequent determination of blood sugar is essential for diabetics as part of a self-monitoring program. A high success rate is desirable for such self-monitoring programs without an unnecessary consumption of test devices.